How to determine stability (and buoyancy) of a very slender boat?

Discussion in 'Stability' started by JotM, Mar 25, 2009.

  1. JotM
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    JotM Junior Member

    Hello all,

    Can anyone give me a hint as to how one is supposed to assess the stability and buoyancy of a very slender (small) boat with respect to the RCD? (EN) ISO 12217 excludes any boat with a beam of less than 1,1 m from its scope.

    I am trying to figure out how to meet demands for a sailing canoe. According to the definition of the RSG* for a canoe, a sailing canoe no longer qualifies as a canoe as stated under art 1.3(b) of the RCD and thus should be certified as CE.

    So, what would be the demands to meet and how should that be assessed?

    * RFU #62
     
  2. dskira

    dskira Previous Member

    To have rules for a sailing canoe is a little overkilling.
    Do you have to have to certifie your bathtub with the CE regulation? (ISO bathtub123)
    I am not making fun of you JotM, far from it, I am sad for you. It seams over there every time you want to sail, you have the whole CE up your ***. It is a sad state of affair.
     
  3. marshmat
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    marshmat Senior Member

    dskira: not sure about the ISO, but if you're certifying a bathtub, try:

    IAPMO IGC 217-2007 Metallic Bathtubs And Whirlpool Bathtubs
    ASME A112.19.7-2006 Hydromassage Bathtub Appliances (Revision of ASME A112.19.7M-1995)
    JIS A 5712:1994 Glass fiber reinforced plastic bathtubs connected with floor (FOREIGN STANDARD)
    ANSI Z124.1.2-2005 Plastic Bathtub And Shower Units
    CSA C22.2 Number 218.2-93(R2004) Hydromassage Bathtub Appliances
    ANSI Z124.8-1990 Plastic Bathtub Liners

    (yes, I definitely just copy-pasted the output of a standards search engine.)

    JotM: Frankly, I don't have a clue how one would assess a sailing canoe for CE purposes. Stability? In a monohull less than three feet wide?
    Transport Canada has a little guide to understanding ISO 12217 ( http://www.tc.gc.ca/marinesafety/debs/vessel-stability/guidelines-iso-12217-1.htm ) but I didn't see much there that would help you....
     
  4. terhohalme
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    terhohalme BEng Boat Technology

    If your sailing canoe is a racing boat by some rule, RCD doesn't apply.

    Edit: if its beam is lover than 1.1 m, it is a toy and RCD doesn't apply
     
    Last edited: May 5, 2009
  5. JotM
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    JotM Junior Member

    LOL - To me, all recreational craft are toys

    But the Recreational craft Sectoral Group (RSG), a group instigated by the Commission to advise on the use of the RCD didn't feel so good about not having "canoe" defined, while "canoes" are excluded from the directive.
    (Perhaps it is good to realize that the members of the RSG are mainly RCD surveyors / notified bodies, so they have an interest in having not to much craft excluded from their services.)

    So they came up with a definition. A quite defective one in my book, but who am I? The definition they have come up with is: "Canoes and kayaks are crafts which are narrow (Bh <1.1m), pointed in both ends, intended for paddling and which do not have fixed points for engines, more than one oar or sails."
    So, a sailing canoe is not a canoe by this definition.

    I have have begun to wonder lately about the ratio behind all of this.

    A canoe is excluded from the workings of the RCD because, as the Commission states in the comments to the RCD "The exclusions in (b) concern types of watercraft, which are by nature incompatible with some of the essential requirements but whose inclusion in the directive might be debatable. Canoes and kayaks, gondolas and pedalos are considered to be craft designed to be propelled by human power excluding rowing. Rowing is considered to be the use of more than one oar. If canoes are so designed and constructed that they can be fitted with an engine and placed on the market as such, they are covered by the directive.".

    If a canoe, is "by nature incompatible with some of the essential requirements", how on earth does it become compatible by adding two oarlocks or a mast step? My guess is, it doesn't. My second guess is, there isn't really a ratio behind all of this.

    Which brings us back to the first comment on this article:
    "Whilst it is for the manufacturer to decide whether or not a boat is covered by the directive ..."
    And my third guess is, when I feel like selling a home made sailing canoe within five years after building it, it is intended to be raced.
     

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    Last edited: May 5, 2009
  6. jehardiman
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    jehardiman Senior Member

    JotM, obviously it is not a canoe then, it is a surfboard! see Article 1(3)(c). Notice there is no statement of what defines a "surfboard", and some of the sinker boards are in effect "canoes"
     
  7. Ad Hoc
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    Ad Hoc Naval Architect

    JotM
    As J.ehardiman noted, see 1(3)(c).
    This code (94/25/EC) does not use the definition of beam, it uses length to define its applicability. Do not mix and match codes, as such use their definitions. So, where your boat does not meet any aspect of this code, see 1(3)(c).
     
  8. JotM
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    JotM Junior Member

    jehardiman and ad hoc, thx!

    @ad hoc: I am not mixing codes. I am fully aware of the fact that the RCD is basically applicable on all craft >2,5 m (and <24 m) in length.

    For a sailing canoe as such, standard (EN) ISO 12217-3:2002 Small craft — Stability and buoyancy assessment and categorisation — Part 3: Boats of hull length less than 6 m or (EN) ISO 12217-2:2002: Small craft — Stability and buoyancy assessment and categorisation — Part 2: Sailing boats of hull length greater than or equal to 6 m would typically be used in order to achieve "presumption of conformity" ex. art 5 of the RCD.

    EXCEPT, these standards both state: "1 SCOPE ... this part of ISO 12217 excludes: ... - canoes, kayaks or other boats with a beam of less than 1,1 m ...". I am not introducing beam, but the applicable harmonized standards and the recommendation for use #62 (by the RSG) are.
     

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  9. Ad Hoc
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    Ad Hoc Naval Architect

    JotM
    The 94/25/EC code is dated 16th June 1994.
    The RFU is dated 11th May 2007.

    There is a degree of lag in the administration. However, given their clarification, a canoe is a double ended pointy thing with a beam less than 1.10m.

    As such if your canoe has less than the 1.10m beam, you are not required to conform to the code.
     
  10. JotM
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    JotM Junior Member

    ... "AND which do not have fixed points for engines, more than one oar or sails".

    The devil is in the tail. Fixed points for more than one oar (oarlocks)/sails (maststep) -> not a canoe -> no exemption -> RCD applicable.

    But I am still wandering what might be sensible stability demands for slender craft with a beam < 1,1 m. Not only sailing canoes, the same goes for slender pulling boats in the tradition of Adirondack guide boats, St. Lawrence River skiffs, Whitehalls etc. Any thoughts?
     
  11. Ad Hoc
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    Ad Hoc Naval Architect

    JotM

    Well, is your canoe a "canoe" or is it going to have an engine?...if so, you can't escape the clause about engines etc (yes i saw that). But if not, and it appears to fall into the grey zone, just apply for an exemption, simple. Rules are ostensibly a frame work to provide guidance. As such they are parametric and some designs will invariably fall outside the parameters. When this occurs, apply for an exemption. I have done so many times in the past, successfully too.
     
  12. jehardiman
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    jehardiman Senior Member

    Copies of historical types are expempt IIRC.
     
  13. jehardiman
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    jehardiman Senior Member

    Copies of historical types are expempt IIRC.
     

  14. fcfc
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    fcfc Senior Member

    There are no EU unified rules for craft smaller than what is defined in RCD.

    You have to check national rules.

    For France, every thing smaller than RCD is a beach toy, except craft at least 4m length and 45cm wide, powered by paddles or oars, unsinkable, with positive stability when flooded , self bailing cockpit or skirt, and reboardable by the crew at sea.
    Auxiliary sails are allowed. (at least on kayak).
     
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